The objectives of this project are (1) to identify by chemical and immunochemical techniques the tissues of origin of the triglyceride lipases which appear in human plasma after heparin administration; (2) to quantify tissue-specific triglyceride lipases present in normal and post-heparin plasma; and (3) to investigate the presence or absence of the lipoprotein dependent triglyceride lipases in liver and adipose tissue and post-heparin plasma from patients with hyperlipoproteinemia. The enzymatic mechanisms by which plasma lipoproteins are metabolized and interconverted are poorly understood. Such information appears to be essential to identify aberrant processes and disease states and to devise favorable schemes of therapy to regulate abnormal lipid metabolism associated with hyperlipoproteinemia and atherosclerosis.